1. Technical Field
The present invention relates to a sliding part, such as a chain for vehicle, in which plural links are connected by pins.
2. Background Art
A chain for transmitting power from a driving portion to a driven portion is formed by connecting plural links endlessly by pins. The link and the pin are assembled so as to rotate with respect to each other, and the inner peripheral surface of the link and the outer peripheral surface of the pin slide relative to each other while the chain is in operation. A type of chain called a “silent chain” is widely used as a driving chain for vehicles, such as a chain for camshafts, a chain for oil pumps, a chain for balancer shafts, and the like, and the silent chain does not make very much noise. Such a chain must exhibit low levels of elongation due to wear due to the link and the pin sliding relative to each other and becoming worn (see Japanese Unexamined Patent Application Publication No. 2006-132637).
The above patent document discloses a chain in which an inner peripheral surface of a link is formed with a film of CrC (chromium carbide), and an outer peripheral surface of a pin is formed with a film of VC (vanadium carbide) so as to harden the surfaces and prevent wear elongation. Recently, chains are required to have high strength and high wear resistance.